MnSe - Molecular Beam Epitaxy Growth and Optical Characterisation

Here, we report on the optical properties of manganese selenide (MnSe) layers grown by molecular beamepitaxy. We compare MnSe film growths onc-plane Al2O3in various conditions. Samples were analyzedin situusing reflection high energy electron diffraction. This technique confirmed that in specific conditions growth ofcrystals well oriented to the substrate is possible and the surface of such crystals became flat after tens of nm,with typical grain size dependent on growth time. Further we studied samples using room temperature opticalspectroscopy. Intensity of broad peak observed in photoluminescence spectra is strong for samples with largeMnSe crystallites and very weak for samples with small crystallites. Origin of this peak is attributed to Mn2+d–dtransitions strongly hybridised with Se shells. Thanks to the transparency of Al2O3, transmittance measurementshave been performed on obtained layers, revealing a broad absorption band in blue spectral range, which explainsthe yellow color of MnSe layers. Properties observed in transmittance and the Raman scattering — large band gapand the Raman lines close to 250 cm−1are in agreement with the data reported for the most stable polymorph ofMnSe — rocksalt structure (alpha-MnSe).